Coherent and broadband enhanced optical absorption in graphene

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Y. Nikitin, F. Guinea and L. Martin Moreno, Appl. Phys. Lett., 2012, 101 ... G. Pirruccio, G. Lozano, L. Martin Moreno and J. Gomez Rivas, submitted. V. G. Kravets ...
Coherent and broadband enhanced optical absorption in graphene Giuseppe Pirruccio [email protected]

www.amolf.nl/surfacephotonics

Acknowledgments Funding: Luis Martin Moreno Gabriel Lozano Jaime Gomez Rivas

Outline Motivation and introduction Coherent absorption Measurements and modeling Optimization Conclusions

Motivation Graphene based photodectors: Absorbs from UV to THz High carrier mobility

Problem: the low absolute value of the absorption of graphene (2.3% of the incident light) limits the photocurrent efficiency F. Xia, T. Mueller, Yu. Li, A. Valdes-Garcia and P. Avouris, Nat. Nanotech. 2009, 4, 839. F. Bonaccorso, Z. Sun, T. Hasan and A. C. Ferrari, Nat. Photon., 2010, 4, 611.

Enhanced photodetection

Not ideal for broadband absorption

Microcavity realized through Bragg mirrors (optimized for narrow wavelength - angular window) M. Furchi, et al., Nano Lett., 2012, 12, 2773 M. Engel, M. Steiner, A. Lombardo, A. C. Ferrari, H. v. Lohneysen, P. Avouris and R. Krupke, Nat. Commun., 2012, 3, 906.

Hybrid devices

G. Konstantatos, M. Badioli, L. Gaudreau, , J. Osmond, M. Bernechea, F. P. Garcia de Arquer, F. Gatti and F. H. L. Koppens, Nat. Nanotech., 2012, 7, 363. Z. Fang, Y. Wang, Z. Liu, A. Schlather, P. M. Ajayan, F. H. L. Koppens, P. Nordlander and N. J. Halas, ACS Nano, 2012, 6, 10222

Plasmonics to enhance absorption

S. Thongrattanasiri, F. H. L. Koppens and J. Garcia de Abajo, Phys. Rev. Lett., 2012, 108, 047401. Y. Nikitin, F. Guinea and L. Martin Moreno, Appl. Phys. Lett., 2012, 101, 151119.

Outline Motivation and introduction Coherent absorption Measurements and modeling Optimization Conclusions

Scattering problem Perfect energy transfer between incoming channels (optical modes) and the structure.

Building a destructive interference pattern in the far-field will cause the light to be trapped in the structure. The material losses will eventually dissipate the energy.

(ωinc, k inc) Weakly absorbing material

Coherent Perfect Absorption 2 channels CPA

Weakly absorbing material

W. Wan, Y. Chong, L.Ge, H. Noh, A. Douglas Stone and H. Cao, Science, 2011, 331, 889.

From 2 to 1 channel 1 channel CPA (single port reflector) Perfect mirror Absorbing cavity

Mirror Absorbing cavity

Total internal reflection Graphene (multi)layer

W. Wan, Y. Chong, L. Ge, H. Noh, A. Douglas Stone and H. Cao, Science, 2011, 331, 889.

Outline Motivation and introduction Coherent absorption Measurements and modeling Optimization Conclusions

Graphene characterization 10 layers

10 layers 5 layers 5 layers 1 layer

1 layer

CVD deposition of graphene on copper foils. PMMA transfer onto silica substrates (turbostratic deposition)

G. Pirruccio, G. Lozano, L. Martin Moreno and J. Gomez Rivas, submitted. V. G. Kravets, A.N. Grigorenko, R. R. Nair, P. Blake, S. Anissimova, K. S. Novoselov and A.K. Geim, Phys. Rev. B, 2010, 81, 155413

Sample

dsilica = 590 – 1300 nm

Magnetron-sputtering in steps (low temperature on graphene)

θ c , 2 < θ c ,1

Absorptance measurements Absorptance (5 layers)

When θ*